Renal failure resulting from chronic glomerular disease is an important cause of death and disability in the United States. The adult idiopathic nephrotic syndrome is a sub-type of chronic glomerular disease uniquely suited for study with an aim to identifying causes of glomerular injury and evaluating the effectiveness of therapy. We therefore are conducting a multi-center collaborative controlled study of the adult idiopathic nephrotic syndrome with an aim: 1. To correlate the clinical manifestations, course, and response to therapy of patients with nephrotic syndrome with the specific pathological changes observed in kidney tissue. Standardization of data collection over a three year period, and renal biopsy with light, immunofluorescence, and electromicroscopic techniques will be utilized. 2. To ascertain whether measurable, statistically significant benefits in mortality and morbidity are conferred within the period of observation by currently proposed therapeutic agents. 3. To establish an organization of cooperating investigators and hospitals, and a framework for the controlled study of renal disease that might ultimately be extended to other investigations.